2006 W219 CLS 350 M272 CGI High Oil Consumption

[EugeneP]

Hello everyone,

In March of this year, I bought a 2006 W219 Mercedes-Benz CLS 350 CGI. During the pre-purchase inspection, everything seemed okay. The engine ran smoothly, the transmission shifted well, there were no visible oil leaks, and no smoke was coming from the exhaust.

However, about a week after buying it, I got a dashboard message to check the oil level at the next refuel.

To cut a somewhat long, but boring story short, over the past 5 months and ~10,500 km (~6,500 miles) of driving, the car has consumed roughly 10 litres (2.6 UK gallons) of 5W-40 oil, averaging around 1 litre per 1,000 km (~1 quart per 600 miles).

About 2,000 km (~1,200 miles) ago, the engine developed a misfire on cylinder 6. The culprit was a heavily fouled spark plug, so I replaced all six. My mechanic told me that the fouling was directly caused by the high oil consumption (While he was in there, he could have also checked whether there was any cylinder scoring, but oh well.)

I know PCV/breather valve replacement is the standard advice for M272 oil consumption, but the setup on the CGI version seems significantly more complex and difficult to access than on the standard M272. Given how supposedly rare the CLS CGI variant is, finding other specific parts has also been tricky and expensive. I did find a forum post detailing a similar issue (E350 M272 CGI a lot of oil going somewhere), but the owner later noted in other posts and comments that changing the PCV valve ultimately didn't resolve their oil consumption.

Before committing to doing anything, I’d appreciate any guidance:

• What diagnostic steps should I take to pin down where the oil is going (valve stem seals, PCV)?
• Has anyone successfully cured high consumption on the M272 CGI specifically?

I just inspected the inside of the hose connected to the PCV spout as well. While there was some oily residue inside, I didn't see a huge build-up or heavy pooling, at least near the start of the hose.

Thanks in advance for any insights!

 

[ALFAitalia]

I dont know that engine or have an answer Im afraid....but you do need to get it sorted ASAP or all that burnt oil going through it is going to contaminate or damage your cat which could lead to an MOT fail on emissions. As Im sure you are aware, new cats are far from cheap with Mercedes....at over £1000 for a genuine one.

 

[Wighty]

https://mercedes-specialist.uk/blog/mercedes-m272-balance-shaft

 

[Skipp]

My reply is all a bit "AFAIK"..nothing definitive to add, sorry.

FWIW, if the seller had put the wrong viscosity oil in the engine that could contribute to high consumption.
Also, 1 litre of oil per 1000 miles does not sound catastrophic to me, afaik there are a few engines around 3.5 size can consume up to a litre per 1000 miles. Pretty sure Ive had a few.

However, afaik oil on a spark plug usually suggests a seal, either piston ring or valve seal.

 

[ALFAitalia]

I dont think a litre per 1000 ml is acceptable on any engine. I know it says that it is in some handbooks....but thats only to cover the warranty dept from claims of no oil where the customer didnt check "it says a litre per thousand miles in the handbook sir....do you check every 1000 miles?....no?....oh dear....".....as some engines burn a fair bit when brand new. Early VW TDI engines for example were known for burning a bit when new.... then none after about 10,000 miles.

 

[Skipp]

I dont think a litre per 1000 ml is acceptable on any engine. I know it says that it is in some handbooks....but thats only to cover the warranty dept from claims of no oil where the customer didnt check "it says a litre per thousand miles in the handbook sir....do you check every 1000 miles?....no?....oh dear....".....as some engines burn a fair bit when brand new. Early VW TDI engines for example were known for burning a bit when new.... then none after about 10,000 miles.

We all have opinions, including those people that write the owners manuals.

Pretty sure that my 3 of my recent cars had a manual that stated categorically that 1000ml per 1000miles, even 1500ml was acceptable and not to be a concern. But it is car specific.

I also thought that dieseasal engines used oil as part of the combustion cycle.

I could be wrong. It won't be the first or last time.

 

[ALFAitalia]

My car burns no oil between services....but then I change the oil about every 5000 miles so id like to hope not. Dervs do not use engine oil in the combustion process and generally burn no more oil than petrol engines....they do tend to have a bigger oil capacity though.

As said above they say that to passify the warranty dept.

From the AA.

Manufacturer Stance: Many carmakers list 1 litre per 1,000 miles (or 1 litre per 1,000 km) in the manual as a legal threshold to protect themselves against warranty claims.

Real-World Expectation: Most healthy modern engines use far less—often needing little to no top-up between regular 10,000-mile services.

Exceptions: High-performance sports cars with turbocharged engines, or older vehicles with high mileage may naturally burn more oil during regular operation.

 

[Skipp]

Thanks for clarifying that. I will take AA experts over my amateur opinion any day.
I mixed up diesel with two-stroke - two-strokes use oil afaik not diesel.

I also took the moment to learn a bit about valve seals.

Whilst I did, I picked up this comment specific engine : you might want to check the plastic centrifugal oil separator on the back of the passenger-side cylinder head. A cheapish part that can fail and confuse issues. Might want to sanity check that ****, AI told me that It certainly wont know which side the passenger side is in the OP's car.

 

[mioba]

If diesels used oil while driving you wont stop the car - diesel runaway.

That said. You have excessive oil consumption. No ifs about it and forget the handbook.

Cylinder 6 says it all.

Measure compression. Then do a leak down test.

Could be rings, oil scrapers, valve stems - but the above diags will help identify.

cant think why it would be the PCV.

seeme like the seller knew of the problem.....